Is bigger always better? When it comes to designing a small, lightweight carbine with the ability to quickly change barrel lengths or configurations, the AR15/M16 series rifle is an ideal base platform that allows modification according to current need. PWS (Primary Weapons Systems) is known for manufacturing effective piston conversions, compensators and complete AR15/M16 series upper receivers.  PWS recently released the Diablo, a 7-inch piston upper for the AR15/M16 series rifle. Without getting into the debate of direct impingement versus gas impingement systems in the AR15/M16 platform, the bottom line is that the PWS Diablo works, and it works well.

The genesis of the Diablo was the desire to make the AR15/M16 rifles as short as possible without affecting reliability, while at the same time maximizing accuracy and effectiveness. Rather than simply taking commercially available parts, bolting together a new product and calling it revolutionary, PWS designed a system from the ground up to work specifically with the extreme pressures of the 7-inch barrels.

Upper Details
The commitment to quality and reliability is demonstrated through the use of components used to build the Diablo. At the center of the upper receiver is a Vltor MUR (Modular Upper Receiver). Dean Sylvester of PWS explained that any upper receiver could have been used, but Vltor offers a high quality product that could not be found in other commercially available products. In addition, the Vltor MUR receiver features a thicker wall to provide increased accuracy and reliability while also extending the life of the bolt carrier group and barrel assembly.

Accuracy from a small package was of foremost importance. Sylvester said, “Accuracy and reliability were the paramount concern when I designed the system. I ultimately decided on a 7-inch stainless barrel, polygonal bore with a 1-in-8-inch twist. The twist was used to give the ability to shoot both light and heavy loads without sacrificing accuracy.